Method and system for venting load lock chamber to a desired pressure

Abstract

A system and method for reducing particulate contamination during the loading and unloading of semiconductor substrates into a load lock chamber of a semiconductor processing tool provides one or more pressure sensors that measure the actual ambient pressure in the fabrication facility or within a discrete environment within the fabrication facility and determine a crossover pressure to be used to open a load lock chamber door after the load lock is vented. The crossover pressure is determined by an input indicating a relationship between the desired crossover pressure and a detected ambient pressure. The crossover pressure may be identical to, greater than, or less than the measured ambient pressure. The ambient pressure may be measured on an ongoing or real-time basis.

1 . A method for venting a load lock chamber of a semiconductor processing tool, comprising:
 detecting ambient pressure outside said semiconductor processing tool;   determining a desired load lock crossover pressure based on said detected ambient pressure;   purging said load lock chamber with an inert gas until said load lock chamber achieves and stabilizes at said desired load lock crossover pressure; and   opening an external load lock door after said load lock chamber stabilizes at said desired load lock crossover pressure.   
   
   
       2 . The method as in  claim 1 , wherein said desired load lock crossover pressure equals said detected ambient pressure. 
   
   
       3 . The method as in  claim 1 , wherein said desired load lock crossover pressure comprises a pressure of about 20,000-30,000 millitorr greater than said detected ambient pressure. 
   
   
       4 . The method as in  claim 1 , wherein said desired load lock crossover pressure comprises a pressure that is about  1  percent greater than said detected ambient pressure, in millitorr. 
   
   
       5 . The method as in  claim 1 , wherein said determining comprises a processor performing a mathematical calculation using said detected ambient pressure. 
   
   
       6 . The method as in  claim 1 , wherein said determining comprises inputting to a processor a mathematical relationship between said desired load lock crossover pressure and said detected ambient pressure and calculating said desired load lock crossover pressure therefrom. 
   
   
       7 . The method as in  claim 1 , wherein said determining comprises accessing said detected ambient pressure stored in a memory of a processor; and further comprising transporting semiconductor wafers through an external opening formed when said load lock door is opened. 
   
   
       8 . The method as in  claim 1 , wherein a first external sensor is used for said detecting ambient pressure and a second internal sensor is used for determining when said load lock chamber achieves and stabilizes at said desired load lock crossover pressure. 
   
   
       9 . The method as in  claim 1 , further comprising delivering a signal to said load lock chamber to vent and open said load lock door and wherein said detecting ambient pressure is performed responsive to said delivering. 
   
   
       10 . The method as in  claim 1 , wherein a pressure sensor is disposed in said load lock chamber and said detecting ambient pressure comprises measuring said ambient pressure using said pressure sensor when said load lock chamber is opened. 
   
   
       11 . The method as in  claim 10 , wherein said detecting ambient pressure takes place when said load lock door is opened during loading of a first run and said purging said load lock chamber with an inert gas until said load lock chamber achieves and stabilizes at said desired load lock crossover pressure, takes place during one of unloading of said first run, and loading of a subsequent run. 
   
   
       12 . The method as in  claim 1 , wherein said measuring ambient pressure comprises said ambient pressure being a pressure in a discrete environment within a semiconductor fabrication production facility. 
   
   
       13 . The method as in  claim 1 , wherein said detecting ambient pressure takes place substantially continuously, and said determining determines said desired load lock crossover pressure based on a most recently detected value of said ambient pressure. 
   
   
       14 . A system for venting a load lock chamber of a semiconductor processing tool, said system comprising:
 a pressure sensor capable of detecting ambient pressure outside said semiconductor processing tool;   means for determining a desired load lock crossover pressure based on said detected ambient pressure;   a venting system capable of purging said load lock chamber until said desired load lock crossover pressure is achieved and stabilizes in said load lock chamber; and   an actuator capable of opening an external load lock door responsive to said desired load lock crossover pressure stabilization in said load lock chamber.   
   
   
       15 . The system as in  claim 14 , wherein said means for determining a desired load lock crossover pressure include input means for receiving a mathematical relationship between said measured ambient pressure and said desired load lock crossover pressure. 
   
   
       16 . The system as in  claim 15 , wherein said mathematical relationship provides that said desired load lock crossover pressure is one of the same as and within a range of about 20,000-30,000 millitorr greater than, said detected ambient pressure. 
   
   
       17 . The system as in  claim 14 , wherein said ambient pressure comprises a pressure in a discrete environment within a semiconductor fabrication production facility and further comprising a controller that sends a signal to said actuator responsive to said desired load lock crossover pressure stabilization. 
   
   
       18 . The system as in  claim 14 , wherein said pressure sensor is disposed inside said load lock chamber and detects said ambient pressure when said external load lock door is opened. 
   
   
       19 . The system as in  claim 14 , wherein said semiconductor processing tool comprises one of an etching tool and a deposition tool, said venting system is capable of purging said load lock chamber with an inert gas and said means for determining a desired load lock crossover pressure includes a processor that calculates said desired load lock crossover pressure based on an input relationship between said desired load lock crossover pressure and said detected ambient pressure. 
   
   
       20 . The system as in  claim 14 , wherein said pressure sensor is disposed external said semiconductor processing tool and further comprising a further pressure sensor disposed in said load lock chamber, said further pressure sensor capable of detecting pressure in said load lock chamber.